A typical radar system transmits an electromagnetic signal and receives back reflections of the transmitted signal. The time delay between the transmitted and received signals can be determined and used to calculate the distance and/or the speed of objects causing the reflections. For example, in automotive applications radar systems can be used to determine the distance and/or the speed of oncoming vehicles and other obstacles.
Modern radar systems often use modulated radar signals to increase sensitivity. Some such systems use repeating modulation schemes, where the radar signal is modulated in a repeating periodic frame-by-frame pattern. While such radar systems can provide increased sensitivity, they can be susceptible to certain types of interference. Such systems will thus commonly include filters in the radar receivers to help avoid interferences. For example, in some radar receivers, high pass filters with low cut-off frequencies are often used to attenuate low frequency interferences. In automotive applications these filters can be used to avoid the “bumper effect” that can be caused by reflections from car bumpers.
Unfortunately, such radar systems can be susceptible to saturation in the radar receivers. In general, saturation occurs when the input to an amplifier rises above a maximum input voltage. Such an input causes the amplifier to produce a maximum allowable current and/or voltage, a situation commonly referred to as “clipping”. Because the output of the amplifier is at the maximum level, no usable data is produced while the amplifier is in saturation. In a radar receiver, such saturation can cause a temporary “blindness” of the radar receiver. Saturation is particularly problematic if the saturation extends across multiple frames of the transmitted signal. In modulated radar systems the frame period can be relatively short, and thus in those systems saturation can significantly impede the proper functioning of the radar device.